There are multiple things for this - the general approach would be the logs (they are used in
game tutorial #38), which allow you to gather information and display them in a log menu. Logs consist of log texts, which you can learn/add via the event system.
The bestiary can collect information about combatants, it's introduced in
game tutorial #49.
Finally, you can also use ORK's quest system, for something like this, though I'd say it's best used just for quests :)